A Bruker Apex III reflectron matrix-assisted laser desorption/ionization (MALDI-TOF) mass spectrometer (MS) fitted with ultraviolet (nitrogen, 337 nm) and infrared (Er-YAG, 2.94 um) lasers, pulsed ion extraction and post-source decay (PSD) be purchased to serve the needs of six projects that are carried out by a group of nine major users based at Boston University (BU) School of Medicine, BU Goldman School of Dental Medicine (both at the BU Medical Center campus) and the Eunice Kennedy Shriver Center for Mental Retardation, Waltham, MA. These NIH-funded investigators are engaged in (1) determining the templates and nature of post-translational protein modifications leading to cardiovascular disease (Cohen), (2) determining the structure/activity relationships of milk oligosaccharides and glycoproteins that have protective activity for newborns and young children (Newburg), (3) studying proteoglycans in the cornea (Nugent, Trinkaus-Randall) (4) identifying proteins, peptides and other components present in pellicle, the first site of attack and defense on the tooth surface (Oppenheim, Troxler), (5) understanding the proteomic consequences of exposure to cigarette smoke (Taccioli), and (6) characterizing deposits and circulating proteins resulting in amyloid diseases that arise from fibrillogenesis of immunoglobin light chain fragments following indolent plasma cell dyscrasia in the bone marrow (AL), of serum amyloid A protein (systemic amyloidosis, AA) and of the serum protein transthyretin in patients having inherited genetic mutations (familial amyloidotic polyneuropathy, FAP or ATTR), or advanced age (senile cardiac amyloidosis, SCA) (Walsh, Skinner) A group of six minor users at BUMC and other nearby institutions also have need for state-of-the-art MALDI-TOF MS analysis to support studies in Alzheimer's Disease (Abraham), transition states and intermediates in enzyme catalysis (Allen), protein N-glycosylation pathways (Kukuruzinska), the thrombin receptor (Kuliopoulos), presentation of non-peptid antigens to T-cells (Moody) and lipids and apolipoproteins related to atherosclerosis (Small). The Reflex III MALDI-TOF M will be housed in the BUSM MS Resource. Priority will be given to the projects described; minor users at BUMC and the B main campus, as well as the large Resource community will be served in the remaining time. The instrument will be operated and maintained by experienced personnel already associated with the laboratory. The Resource has a strong record for collaboration and education and will assure that users of this instrument system are integrated into these programs.